C2 Front / Rear alignment specs

[Richard E.]

What alignment specifications (Front & Rear) would be suitable for radial tires; P205-70-R15 on a 66 roadster?
Basic configuration is; with 300hp - 327, with automatic transmission, with power steering, no air conditioning, no hard top, no high performance options.

I expect the specs in the AIM would not be best for radials.

Caster, camber, toe in, and any comments appreciated.

Thanks much.

[Gene M.]

Re: C2 Front / Rear alignment specs

Richard, I like 1/16 -1/8" toe, as close to zero camber but not more than 1 degree negative. Caster is difficult to get more than 2 degrees but a bit more would be better. One affects the other and it is a compromise. The rear is set about the same for camber and toe. Keep in mind the wider the tire the more added the greater the scuff and wear. Some tires of the same size can be up to an inch wider thread contact.

A good explanation http://www.carparts.com/alignment.htm

[Duke W.]

Re: C2 Front / Rear alignment specs

Front camber: 0 deg.
Front caster: as much as possible up to 2.5 deg. within the adjustment range for power steering.
Front toe-in: 1/32" each side, steering wheel centered

Rear camber: -1/2 deg.
Rear toe-in: 1/32" each side

Cross settings should be as close to zero as possible

205/70R-15 tires are shorter than OE and have higher revs/mile, which will increase speedometer error about 5 percent on the high side. You should choose either 215/70R-15 or 205/75R-15. Within these size ranges there are no longer any "performance" tires, but you might be able to find a H-rated 215/70R-15, which is my recommendation if you can find one.

There have been dozens of threads on tires and alignment over the years, so do some searching.

Duke

[Richard E.]

Re: C2 Front / Rear alignment specs

Thanks very much Gene & Duke. I will be replacing the tires (205/70R-15) so if anyone can recommend a brand for the 215/70R-15 or 205/75R-15 I'm open to suggestions. My preference is for a non aggressive street tread with about a 3/4" whitewall. That really seems difficult to obtain. Not much in whitewalls available and most "all season" tires look like they should be on a garden tractor (just my opinion, I'm old fashioned I guess).

Thanks again.
Rich

[Richard E.]

Re: C2 Front / Rear alignment specs

Duke,
I plan to install adjustable strut rods, and the instructions call for a base setting of 3 degrees rear camber plus or minus 0.5 degrees. I expect this is negative camber, the instructions do not specify. This is much different than the spec. of -1/2 degree. Any reason for this difference? Possibly the instructions are for bias ply tires?
Also, I'm looking at Cooper P205/75-R15 tires (whitewall), not high performance but seem adequate for regular driving. Any thoughts on these tires (size etc.) are appreciated.
Thanks much.

Rich

[Duke W.]

Re: C2 Front / Rear alignment specs

If their recommended camber doesn't even specify positive or negative you have to assume these guys have their head in a dark place. Why not install a set of OE strut rods, get the rear alignment setup as recommended with fasteners properly torqued to spec, and you are done.

My "sport" alignment settings call for negative one degree camber at both ends, and that's about the limit you can run negative on a road car without suffering excess inside shoulder wear. BTW, these are also the initial settings GM recommends for a road racing setup.

Negative 3 degrees cam is an EXTREME setting that would only be useful (maybe) on a dedicated autocross car.

Aftermarket suspension parts are as bad as aftermarket camshafts, all of which I recommend avoiding.

There are a lot of P205/75R-15 tires to choose from, and all that I am aware of are "S" speed rated, lack a spiral would nylon cap belt, and have rock hard compounds as evidenced by a wear rating of 500 or more. I call them "van tires", and they are all pretty much the same, so choose based on price and appearance.

My preference would be a H-rated 215/70R-15 that has a nylon cap belt. I think there might be one or two available, but they are likely blackwall, which is also my preference. You can Google the tire size and search the big Web tire retailer for candidate sizes to see what's available at the present time.

Duke

[Richard E.]

Re: C2 Front / Rear alignment specs

Thanks for your comments Duke. In the future I will likely install OE strut rods. When I purchased the car it had a glass spring & aftermarket adjustable struts. I am re-aligning because of recently replacing rear wheel bearings both sides. One strut rod is "frozen solid" I expect because the previous owner did not apply anti-seize to the threads (never experienced anything so tight, will just replace both struts as a result).

Rich